This invention relates to a welding power supply system for use in inert gas arc welding, and has particular application to inert gas metal arc welding using nonconsumable electrodes, such as tungsten, commonly referred to as tungsten inert gas (TIG) welding, and is used in welding aluminum, aluminum alloys and similar metals.
The basic reasons for using square wave TIG welding are well known in the prior art, as described in U.S. Pat. Nos. 2,495,655; 22,951,930; 3,068,352; 3,300,683; 3,330,933; 3,349,219; 3,350,538; 3,528,100; 3,598,954 and 3,781,508; and British Pats. Nos. 732,230 and 732,403; and "IEEE Transactions on Industry and General Applications," November/December 1967.
The techniques shown in the above mentioned prior art include a single power supply connected to the arc directly or through an inverter; or dual power supplies connected to the arc through a control or switching circuit; or power supplies connected to the arc either directly or through an inverter with the output shunted to control welding current during the reverse polarity interval.